1. Field of the Invention
The present invention relates to a substrate and the method of producing the same and, more particularly to a patterned substrate for epitaxially growing a semiconductor material and a method for patterning a substrate.
2. Description of the Related Art
A conventional substrate for epitaxially growing a semiconductor material is obtained by cutting slices from a single-crystal ingot, and then polishing and chemical washing the cut slices. The substrate thus obtained has unavoidably a residual stress, or defects. Therefore, when an epitaxial layered structure is epitaxially grown on such substrate, the defects of the substrate will propagate to the epitaxial layered structure and affect adversely the quality of the epitaxial layered structure, thereby degrading the working performance of the semiconductor device produced therefrom.
Referring to FIG. 1, to solve the abovementioned problem, it is common to pattern an upper face 11 of the conventional substrate 1 for epitaxially growing a semiconductor material so that the conventional substrate 1 is further formed with a plurality of downwardly indented recesses 12 from the upper face 11 after being cut and polished. The recesses 12 thus formed are spaced apart from one another and arranged periodically. When the epitaxial layered structure is formed on the upper face 11 of the conventional substrate 1, the area of the upper face 11 where nucleation, grain growth and coalescene tend to occur is reduced due to the existence of the recesses 12. Thus, the opportunities of propagation of the defects from the substrate 1 to the epitaxial layered structure are lowered so as to obtain an epitaxial layered structure with an improved epitaxial quality.
However, since there is still some occurrence of nucleation, grain growth and coalescene on the upper face 11 of the conventional substrate 1, the propagation of the defects to the epitaxial layered structure is unavoidable, and the conventional substrate 1 is required to be further improved so as to enhance the crystal quality of the epitaxial layered structure formed thereon.